Cecilia Carey’s set design for Sense of an Ending at Theatre503 is surely one of the best of the year so far – deceptively simple to behold but wonderfully inventive and empathetic to the story it houses. Multi-coloured panels in a false wall initially suggest the evocative beauty of stained glass but as the play progresses, they are sculpted by Joshua Pharo’s lighting into conduits into the past, compelling reminders of the present and suggestions of the future looming over the characters of Ken Urban’s Rwanda-set play.

All three time periods are important but it is the past that is most significant. It’s 1999 and two Hutu nuns stand accused of aiding and/or abetting a massacre in their church in the 1994 genocide that decimated this African country’s population. An American journalist, haunted by his own demons, arrives at the prison they’re being held at to throw attention on their case but in a nation where the healing process has scarcely begun, notions of truth and reconciliation are hard to come by as conflicting accounts cast doubt on their presumed innocence.

There’s a dark, sinuous power to Jonathan O’Boyle’s production which never lets us forget that in times of turmoil, the truth rarely comes in the stark black and white that the hopelessly naïve journalist craves, and that an academic understanding of the issues is no replacement for the deep-seated reality of ethnic conflict. Urban’s writing gives us both, eventually, Ben Onwukwe’s writer has to unravel a fair bit of expositionary dialogue but the pay-off comes in two devastatingly effective scenes of uncompromising starkness.

First, a survivor of the massacre recounts his tale in all its appalling brutality – abandoned by the international community, turned on by his own countrymen, it’s a necessarily hard but vitally important piece of storytelling by Kevin Golding that leaves us reeling. And then late on, the question of forgiveness raises its head and due to the brilliant performances of Lynette Clarke and Akiya Henry as the emotionally complex sisters, the final moments have an enormous and illustrative power that lingers long in the mind.

From the desperately dark humour of Abubakar Salim’s highly charismatic Paul (his deconstruction of the term African-American is very wittily done) to the haunting sight of the nuns sat barely visible behind the glass - ever-present witnesses or perhaps a foreshadowing of them entering the dock – Sense of an Ending has an elegant grace about it that is utterly gripping. As eloquent an exploration of wartime atrocities and their aftereffects as one could hope to see.